Secure physical connections are necessary in many industrial applications, particularly secure connections between metallic parts. The metallic parts can be formed from metal, alloy, or a combination thereof. Typically these types of parts are secured to each other by welding, spot welding, fasteners, rivets, solder, brazing or adhesives. All of these procedures suffer from various drawbacks including cost, efficiency and in some cases the need to keep the parts below certain temperatures. Often these procedures result in heating of the parts, which can be a disadvantage in many applications. In addition, many of these connection methods are time consuming.
Making secure physical electrical connections in structures such as multi-cell batteries is important. These connections are used to connect the cells of multi-cell batteries in series or parallel depending on the needs of the electrical environment in which they are to be used. One type of battery where such connections are of particular importance is a lithium ion multi-cell battery. In the past the terminals of the individual cells of the battery have been secured to one of two bus bars either in a series connection or a parallel connection. Established methods for connecting the terminals to the bus bars include ultrasonic welding, laser welding, capacitive discharge spot welding, soldering, or mechanical means such as crimping. What ever method is chosen it needs to meet several criteria including: the ability to bond dissimilar metals; electrical resistance of the connection that is below about 0.2 mΩ; low cost per connection; the ability to withstand mechanical, thermal; and impact cycling; resistance to corrosion; and the ability to keep the temperature of the cell near the connection below about 100° C. during formation of the connection to prevent thermal damage to the cell. All of the above methods are able to achieve these criteria to some extent; however, none are an ideal solution.
It would be desirable to develop a cost effective method for securing metal parts to each other. Preferably the method will be fast and efficient. In addition, it would be beneficial to develop a method that is able to join a wide variety of metals, alloys, and combinations thereof. It would also be beneficial to create such a method that does not cause large temperature increases in the parts being joined.
It is also desirable to develop a cost-effective, rapid, and reliable method for formation of electrical connections between a multiple of electrical conductors that can readily be adapted to the environment of a multi-cell battery. Preferably, the method will be capable of meeting the criteria set forth above and be relatively easy to implement.